1. Field of the Disclosure
The technology of the disclosure relates to ferrule holders supporting ferrules in fiber optic connector assemblies for providing optic connectors for establishing fiber optic connections.
2. Technical Background
Optical fiber is increasingly being used for a variety of applications including but not limited to broadband voice video and data transmission. Benefits of optical fiber use include extremely wide bandwidth and low noise operation. With the increasing and varied use of optical fibers it is important to provide efficient methods of interconnecting optical fibers. Fiber optic connectors have been developed for this purpose. It is important that fiber optic connectors not significantly attenuate or alter the transmitted signal. In addition, the fiber optic connector should be relatively rugged and configured to be connected and disconnected a number of times in order to accommodate changes in the optical fiber transmission path. The fiber optic connector should also be configured for its environment. For example, outdoor interconnections may require a more rugged fiber optic connector that those designed for indoor interconnections. Because of the skill and equipment required for making optical fiber connections in the field, fiber optic cables are often pre-connectorized with fiber optic connectors for plug and play connectivity.
In this regard, a fiber optic connector typically employs a connector sub-assembly. The connector sub-assembly contains a ferrule holder that holds a ferrule. The ferrule holder has a passage extending therethrough that is axially aligned with a ferrule bore in the ferrule. An end portion of an optical fiber extending from a stripped fiber optic cable is inserted into the ferrule holder passage and into the ferrule bore. After assembly and polishing, the ferrule of the completed sub-assembly is suitable for optical alignment with the ferrule of a complementary connector assembly for establishing an optical connection between optical fibers disposed within the ferrules. More specifically, the optical fiber is held within the fiber optic connector sub-assembly. To firmly secure the optical fiber to the fiber optic connector sub-assembly, a bonding agent such as an epoxy is typically applied to the inside of a portion of the ferrule holder passage before the optical fiber is inserted therethrough. The optical fiber is then inserted into the ferrule holder passage through the bonding agent and into the ferrule bore.
A lead-in tube may be installed at the factory into a concentric inner surface located at a back end of the ferrule holder to facilitate optical fiber insertion. The lead-in tube generally has low flexural stiffness. There are benefits to the use of a lead-in tube. One benefit is that the lead-in tube generally restricts a bonding agent used during installation of an optical fiber into the ferrule to the ferrule holder passage and prevents the bonding agent from escaping. Otherwise, the bonding agent may come into contact with other areas of the fiber optic connector, such as a spring mechanism which must be free to move unfettered by the bonding agent. The lead-in tube also facilitates guiding an end portion of an optical fiber into the ferrule holder passage, where the optical fiber can then be guided to the ferrule. The lead-in tube may also prevent sharp bends from occurring in the optical fiber during insertion that could damage the optical fiber as the optical fiber is disposed in the ferrule holder passage and into the ferrule.
The lead-in tube may be difficult and expensive to manufacture and align to a ferrule holder body due to the tolerances required for use. The lead-in tube may also unexpectedly disengage from the ferrule holder because of friction with a syringe, which is temporarily inserted through the lead-in tube to inject the bonding agent before being removed. Lead-in tubes may also unexpectedly disengage from the ferrule holder because of vibration experienced during shipping. A lead-in tube which is less expensive to manufacture and more efficient to use to engage with a ferrule holder may be desired.